Camera



Oct. 22, 1935. A. c. MAYO 2,017,979

CAMEiIA I Filed Sept. 12, 1934 2 Sheets-Shet 1 Oct. 22, 1935. C MAYO I 2,017,979

CAMERA Filed Sept. 12, 1934 2 Sheets-Sheet 2 177022227 "M "z x a Patented Oct. 22, 1935 UNITED STATES PATENT OFFICE CAMERA Alfred Croger Mayo, Richmond, England Application September 12, 1934, Serial No- 743,775 In Great Britain September 22. 1933 13 Claims. (CL 95-41) to hold a light-sensitive surface close against the back of the picture-aperture in the back-plate, a shutter plate with an exposure-aperture therein, mounted to slide on the front of the back-plate, yielding means to urge the shutter-plate across the picture-aperture, setting means to retract the shutter-plate against said yielding means into "set position at one side of said aperture, a releasable catch to hold said shutter-plate in set position and means associated with said setting means for covering the exposure-aperture in the shutter-plate during movement towards set position but for leaving it uncovered when released.

The means for covering the aperture in the shutter plate may comprise a covering-plate closely overlying the shutter-plate, slidable relatively theretofprovided with an exposure-aperture adapted to coincide with the exposure-aperture in the shutter plate, yieldingly urged in such a direction that said exposure-apertures coincide, and provided with an abutment for engagement with the setting means so that movement in the setting direction causes the covering-plate to slide over the shutter-plate to close the said apertures during the setting operation.

In the preferred construction the back-plate. a shutter plate and the covering-plate are all curved so as to be concave on the side toward Figure 1 is a perspective view of the exterior of a camera.

Figure 2 is a front view with the lens'and the front-plate of the camera removed toshow the shutter.

Figure 3 isa cross-section upon the line 3-3 of Figure 2 looking in the direction of the arrows.

Figure 4 is a perspective detail of the shutter A parts, and

Figure 5 is a view to an enlarged scale of the 5 camera with parts broken away and looking in the opposite direction to that of Figure 3. y

The camera is built up upon two main side plates ll, l2 which are united together by a curved plate l3 passing around the front of two spool spaces l4, l5 and curved rearwardly between the spool spaces nearly to the back of the camera. The plate l3 constitutes a back plate behind the shutter hereinafter described and has a picture aperture l6 cut in it. A spool-holder I1 is provided with slots It to receive the projections usually provided on film spools for vestpocket cameras and at one end outside the plate ll there is a winding knob I9. The spool space and the parts just described are covered in at the back by means of a camera-back 20 provided with two number windows 2|, 22 so that two pictures can be taken for each number on the spool of film. 'The sensitive surface of the film in the camera is held close against the back of the picture aperture IS in the back-plate It by means of light springs 23, 24 on the back of the camera. The front of the camera comprises a front-plate 25 which is curved at its ends to fit around the curved end portions of the plate l3 and which is clamped between the side-plates ll, l2. The edges of the plate 25 fit beneath flanges 2G, 21 formed around the rim of theside plates ll, l2 and thus the curved ends of the front-plate 25 are firmly fixed between the back plate l3 and the flanges 26, 21. It will be observed that at the bottom of the front-plate the plate I3 is bent a little away from it and the back-plate 20 of the camera isinserted at its bottom edge between theback-plate l3 and the front-plate 25. This makes a light tight joint. The side edges of the back 20 overlie inwardly projecting flanges 28 around the rear edges of the side-plates ll, i2 and at the top the back of the camera fits at 29 between the front 25 and the-plate l3, being 5 clipped in place by a spring clip 30. These parts are best shown in Figures 2 and 3.

The front-plate'25 carries a forwardly projecting tubular lens-mounting 3| in which is slidably carried a lens-tube 32, capable of telescoping in the mounting 3|. In the lens-tube is a lens 33 and the lens-tube is resiliently pressed forward by a spring 34. It is covered with a cap 35 held on the mounting Si by means of a'bayonet Joint. when the cap is in place the lens 33 is pushed I5 Y of the forks 55, 51.

inwardly by the cap as shown in Figure 3 but on removal of the cap the lens automatically shoots forward into the position shown in Figure 5 inwhich position it is focussed for average distances. A diaphragm 35 is provided in front of the lens. The front-plate 25 has a rectangular opening 31 behind the lens of adequate size to ensure illumination of the picture opening i5 in the back-plate I5.

The shutter parts are best seen in Figure 4 and they comprise a curved shutter-plate which fits closely but is freely slidable over the back-plate I3. closely over it a covering-plate 4| and the side edges of the plates 45, 4| are overlaid by narrow flanges 42, 43 projecting inwardly from the main side plates ll, l2 of the camera. These flanges may be welded or brazed in place and they are spaced from the back-plate I3 by such a distance as to allow the shutter-plate. 45 and covering-plate 4| to be slid beneath the flanges freely and. without undue play.

The shutter-plate 45 has a rectangular aperture 45 cut across it corresponding in width to the width of the picture-aperture l5 and in length to the aperture required for the desired maximum lengthof exposure to be afl'orded by the shutter. The covering-plate 4| has a similar aperture 45 in it so located that in one position of the covering-plate the apertures 45 and 45 may be made to coincide as shown-in Figure 4. Figure 4 shows the shutter in its set position, ready for making an exposure and the aperture l5 in the back-plate is indicated by a dotted line. It will therefore be seen that in this position the exposure apertures 45, 45 are drawn beyond the picture-aperture l5. In this position the shutter-plate 45 is held by a releasable catch 48 hereinafter more fully described. The covering-plate 45 is yieldingly connected to the shutter-plate by means of a hairpin spring 45 hereinafter referred to. 4

In order to bring the shutter-plate 45 and the covering-plate 4| into the set position as shown in Figure 4 a setting knob 55 is provided carried on a spindle 5| and connected to a setting lever 52. The setting lever 52 comprises a yoke portion-53 which extends across the camera from side to side and two downwardly projecting lever arms 54, 55. The lever arm 54 carries a laterally projecting fork 55 at its lower end and the lever arm 55 carries a similar fork 51. Two cars 55, 55 are bent up from the side edges of the covering-plate 4| so as to enter between the arms Therefore rotation of the setting knob 55 with the lever 53 will carry the covering-plate 4| with it. The lever 53 is retracted by a shutter spring 55 secured at one end of the side-plate l2 of the camera. The spring 55 not only tends to retract the lever 53 from the set position but also to carry with it the covering-plate 4|.

In addition to the above parts the shutterplate 45 is provided with two bent up ears 5|, 52 which lie behind the arms of the forks 55, 51. Furthermore the spindle 5| of the setting knob 55 and with it the lever 53 are movable axially to a slight extent to the left as shown in Figure 4 against the action of a short coil-spring 53, for the purpose of setting the speed of the shutter, as hereinafter described. The releasable-catch 45 is operated by a trigger 55 pivoted at 51 on the-side wall ll. of the camera. The trigger 55 is not mounted directly upon the catch 45 but is pivoted about the same axis therewith The shutter-plate has fitting upon a trigger-plate 55 and the trigger-plate 35 is arranged to overlie the catch-plate 45 so that when the trigger 55 is pressed there will be a slight lost motion and then the catch will be released. The trigger-plate 55 is moreover provided with an arm 55 and bent partly with and Just behind the plane of the front 25 of the camera. The arm 55 carries a flag 15 best seen in Figure 5., Thus the first operation of the trigger 55 is to move the fia'g' and the second op- 10 e'ration "is to release the shutter.

The flag 15 is disposed immediately behind the aperture 34 in the front 25 of the camera through which the light from the lens 33 passes. Consequently the flag 15 acts as an additional precaution against 15 light leakage when the shutter is being set.

- In the operation of the shutter the setting knob 55 is first rotated in the direction shown the picture-aperture l5 until they have passed 30 it. If a rapid exposure is desired, the knob 55 will now be pressed inwardly so that the face 55 may engage the car 52 and prevent the covering-plate 4| being retracted by the spring 55 (when the knob 55 is released by the operator) more than a little way, sufiicient to afford a narrow slit-like opening through the two apertures 45, 45, which are only partially in register with each other. If a longer exposure is required the lmob 55 is not pressed inwardly and the spring 55 will draw the covering-plate 4| back into the position shown in Figure 4. The parts are held from further retraction under the influence of the spring 55 by the catch 45. The shutter is now set and will not be released until the trigger 55 is operated. The camera can be carried in this condition, the cap 35if in position effectually preventing accidental exposure. As a further safeguard against accidental exposure a view-finder 52 is pivotally secured to the sideplate ll of the camera by means of a clamping-plate 53, as shown'in Figure 1, and when the view-finder is folded down as shown in that figure an aperture 54 in the view-finder plate embraces the trigger and positively prevents it from movement. On erecting theview-flnder in the position shown in Figure 2 the trigger 55 is freed from restraint so that the operator can actuate 'it at his pleasure. All that is necessary therefore to make an exposure, if the view-finder be raised, ,is to remove the cap 35 and press the trigger 55. This will displace the flag 15. from behind the aperture 34 and thereafter release the catch 45, thus permitting the shutter-plate 45 and the covering-plate 4|, still retaining their relative position in which they have been set, to slide across the picture-aperture l5 under the influence of the spring 55.

The side-plates I I, I2 and all the intermediate I parts are held together by the aid of only two long screws 55, 51 which pass through the camera from side to side. a

It will be observed that the camera described is constructed from a minimum of parts and provides a focal plane shutter which works in the 1s closest possible proximity to the film being ex,- posed, thus leading to maximum eihciency. Owing to the slight curve on which the illm is laid a me of compensation for the aberration of a sim e lens is provided, and owing to the emciency of the shutter very rapid exposures'can be taken with a relatively small aperture. With a suitable strength of spring when the camera is held in such a position that the shutter-plate 4!! falls during the making of the exposure, speeds of about FE and of a second can be provided. while if the camera is inverted so that the shutter moves upwardly in If the camera be held horizontally, intermediate speeds are obtained of about L 40th and 120th of a second.

By making the apertures 45, 46 of dimensions similar, to those oi. the picture-aperture l6 and providing an auxiliary catch to hold the shutterplate temporarily in the position of the parts in which they coincide with the picture-aperture I it is possible to arrange for time exposures.

--I claim:--

l. In a camera a focal-plane shutter comprising in combination a back-plate with a pictureaperture therein means to hold a light-sensitive surface close against the back of the pictureaperture in the back-plate, a shutter-plate with an exposure-aperture therein, mounted to slide on the front of the back-plate, yielding means to urge the shutter-plate across the picture-aperture, setting means to retract the shutter-plate agains said yielding means into "set" position at one side of said aperture, a releasable-catch to hold said shutter-plate in set position, means for covering the aperture in the shutter-plate comprising a covering-plate closely overlyingv the shutter-plate, slidable relatively thereto, provided with an exposure-aperture adapted to coincide with the exposure-aperture in the shutter-plate, yieldingly urged in such a direction that said exnature-apertures coincide, and provided with an abutment for engagement with the setting means so that movement in the setting direction causes the covering-plate to slide over the shutter-plate to close the said apertures during the setting operation.

2. In a camera a focal-plane shutter as claimed in claim 1, wherein the back-plate, the shutterplate and the covering-plate are all curved so as to be concave on the side toward the camera lens.

8. In a camera a focal-plane shutter as claimed in-elaim 1, wherein the covering-plate is provided with a plurality of positions of attachment so that during exposure a greater or less extent of the exposure-aperture in the shutter-plate is uncovered.

'4. In a camera a focal-plane shutter as claimed in claim 1. wherein the setting meanscomprlse a lever engaged with the'covering-plate to move it back and forth. and the lever is provided with I an abutment to engage a co-operating abutment on the shutter-plate so that when said abutmentson'the lever and shutter-plate are mutually engaged, the covering-plate is held with the exposure-aperture in the shutter-plate partly open. lo while when said abutments are disengaged the exposure-aperture is wholly open. I

' 5. In a camera a focal-plane shutters; claimed in claim 1, wherein the exposure-apertures in the shutter-plate and the covering-plate are made of dimensions adequate to expose the whole area of the sensitive surface simultaneously and an additional time catch is provided which when operated holds up the shutter in a position where the sensitive surface is fully exposed.

6. In a camera a focal-plane shutter as claimed in claim 1, wherein the releasable-catchcarries a flag-plate interposed between the shutter and the camera lens but movedout of the way by the catch when the catch is operated to release the shutter.

'7. In a photographic camera having a focal plane shutter, the combination of a guide-plate with a picture-aperture therein, means to hold a light sensitive surface close against the back of the picture-aperture, a shutter-plate having an exposure aperture therein slidable in front of the guide-plate, a covering-plate slidable relatively to and close against the shutter-plate to cover the exposure aperture therein and means to move the coveringand shutter-plates together (with the exposure aperture closed) across the picture-aperture into a "set" position, to uncover the covering plate from the exposure-aperture and thereafter to return the plates together to 40 make the exposure.

8. In a photographic camera having a focal- I plane shutter the combination of a guide-plate with a picture-aperture therein, means to hold a light sensitive surface close against the back of the picture-aperture, a shutter-plate having an exposure-aperture therein slidable in front of the guide-plate, a covering plate slidable relatively to and close against the shutter-plate. means yieldingly to urge the covering plate into register with the exposure aperture in the shutterplate, setting means to engage the covering plate and slide it to cover said exposure-aperture and thereafter to move said covering plate and shutter-plate simultaneously across said pictureaperture in the guide-plate to set position, means to hold said shutter-plate in set position while allowingmaidrovering plate to move to uncover said exposure-aperture and means to release the shutter-plate so that it and the covering plate .0 return together to make the exposure.

9. In a photographic camera, a combination as claimed in claim 7. wherein means are provided to limit more or less as the operator may determine the extent of uncovering movement of the covering plate, to vary the amount by which the exposure-aperture is uncovered and thus to regulate the eflective time of exposure.

10. A photographic camera body having in combination two side-plates and a fllm guideplate extending from one side-plate to the other to divide the film-holding portion of the camerabody from the lens and shutter, which guide-plate has a central exposure-aperture and is curved so as to be concave toward the lens. being close to plstea ndto curvlnz' forward at its ends to embrace the nlm'spoolu, atlflentheconnectlonotthesldeafford a curved cuide tor the film 4 thohacko! and tor-plate of a, focal plane shutter.

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ALFRED mm. 

